Dave Mellor, Fenway Park’s head groundskeeper and grass guru, was lead designer and sculpter for the topiary crown jewel that is the “B STRONG’’ logo etched into the lush center field lawn during the playoffs.

Mellor, 50, has spent some three decades meticulously tending lawns, spending the last dozen years at Fenway. To hear him describe the process, crafting the iconic ornamental logo that symbolizes Boston’s strength, was basic yard work, almost simple enough for a grade-schooler with a plastic Fisher-Price mower to accomplish.

So, kids, feel free to try this at home on mom and dad’s back lawn. What could go wrong?

“To lay it out, we take flags and outline all the letters,’’ he explained early Saturday afternoon, hours before the Red Sox and Tigers met in Game 1 of the ALCS. “And then we use mowers and hand rollers as connect-a-dots. And then just bend that grass, measure it out . . . ”

And voila, there it is, the gargantuan rendition of the “B STRONG’’ logo that our city has worn as a badge of both honor and defiance ever since the horror of the Marathon bombings April 15. As Michelangelo worked the ceiling of the Sistine Chapel, Mellor has shaped Fenway’s floor into a landscaped piece de resistance, an emerald ode to the fine art of shaping blades of grass into a design that baseball fans worldwide will ponder for as long as the Sox play at home for the remainder of the postseason.

“It’s something I am very honored to have an opportunity to be a part of,” said Mellor, noting that his bosses in the Sox front office first suggested the design. “We have done the Sox logo. We have done the ‘B’. They said, ‘Do you think you can do Boston Strong?’ It was like a fun challenge. I said we’d certainly give it a try.’’

According to Mellor, the key to creating any lawn pattern requires but a couple of basic tools: lawn mower and hand roller. Once the letters are blocked out, and the lawn trimmed to its standard height (typically 1⅛-inches high), it’s mostly the handrollers that create the design — the blades of grass rolled in varied directions to create the optical contrast.

“Any mower will make a pattern in the grass with its blades and tires,’’ noted Mellor. “But our mowers also have rollers on them, so they help lay that grass down. It’s just reflecting that light differently. It’s kind of like vacuuming, running a vacuum over a carpet — it changes the nap of the carpet, how it reflects like it does on your carpet.’’

On a personal level, Mellor in recent years has taken on and conquered much bigger tasks than what the baseball world is watching now.

For starters, he has lost 130 pounds, often joining his good pal, comedian Lenny Clarke, for what the two call their “Fat Guy Lunches.’’

“We share ways to have these lunches, mostly frozen food, like Weight Watchers,’’ said Mellor. “And it just started working out great.’’

But an even bigger challenge was dealing with what was deep inside Mellor’s head, the protracted anguish that for decades prevented him from sleeping but a few hours, often led to nightmares and night sweats sometimes so extreme that he would get up in the middle of the night to change the bedsheets.

Mellor, twice hit by cars over the course of some 14 years, found out only three years ago that he suffered from Post Traumatic Stress Disorder.

“I thought only veterans and warriors from the military could suffer from PTSD,’’ he said.

The onset of the disorder, he said, began with the first car accident in a parking lot in 1981.

“I was walking into McDonald’s,” he recalled. “The car came off the street, hit me, threw me 20 feet in the air, and I landed in the corner by the door of McDonald’s. The car kept coming again at a higher rate of speed, pinned the handrail against my knee and against the wall.’’

And thus began a series of surgeries for leg and back woes that have totaled 37 over the years. The car accidents, the surgeries, and the associated pain, he said, all were enveloped in his PTSD.

It wasn’t until a visit to Mass. General Hospital, where he was undergoing acupuncture as a form of pain management, said Mellor, that he came to realize he had PTSD. Thumbing through a copy of Smithsonian magazine, he came upon a story on the subject, which in the opening paragraph listed the disorder’s 12 most common symptoms. Wide-eyed as he read the story, Mellor quickly counted he suffered 10 of the symptoms over the years.

“The only two I hadn’t had was suicide or drug abuse,’’ Mellor recalled. “And I thought, ‘Oh my gosh!’ And while it scared me, I thought, ‘Maybe there is a treatment for this.’ Because for 29 years, it was a deeply guarded secret that I buried . . . I was scared that somebody might notice a weakness, or that I would be judged, or someone would think less of me.

“And I went home right away and said to my wife [Denise], ‘Honey, we’ve gotta talk.’ I take deep pride in sharing everything in my life with her — she is my best friend. And for years, when I was driving back and forth to college, I would rehearse what I would say to her, how I would bring this up. I didn’t know how to explain it to myself, so I didn’t know how to explain it to her. And before I asked her to marry me, I rehearsed. And before our kids were born, I rehearsed. I just didn’t know how to explain it. And once I read this article, I thought, ‘Hey, maybe this is what this is.’ ”

In short order, said Mellor, MGH doctors confirmed his self-diagnosis. He was soon in twice-a-week psychotherapy sessions, learning, he said, “to densensitze raw, buried emotions.’’

Sure enough, the awful nightmares, most of them dealing with being hit by a car, finally stopped. For the first time in 29 years, said Mellor, he slept through a night, a full seven hours. No nightmares. No sweats. Feb. 10, 2011, was the date. When you haven’t had a night’s sleep in nearly three decades, it’s not hard to commit the date to memory.

So it is little surprise to see Fenway Park’s head groundskeeper wearing a perpetual smile as he tools the ballyard’s grounds. He has a work of art in center field and, most of all, he has his psychological health in check.

As so many victims of the Marathon bombing no doubt must deal with PTSD, he can tell them, proudly, that there is a way back. He only hopes the route home will be faster for them.

“I just want people to know that there is hope out there and that treatment works and people will get better,’’ he said.

“I thought it was an act of weakness to go ask for help, to go see a doctor. But now I realize it takes courage and strength to go through treatment I know, sooner or later, I will go through a new treatment or new trauma. Or I may have an old trauma flare up. But I know now to go seek help and not let it fester for 29 years.

“I really kept it all inside. I didn’t want to burden my family. I didn’t want to burden someone else. I was scared of being judged.

“Now I realize that every one of us is going through our own challenges in different ways. We need to help ourselves first, and it’s important for people not suffer for 29 years in silence like I did.’’